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1. The problem statement, all variables and given/known data

I'm trying to write a lab report about how resistance varies with temperature. I used liquid nitrogen to cool a copper coil and a semiconductor(thermistor) from room temperature to about 120K. I got good results with a linear relationship between the coil resistance and temperature and a linear relationship between ln(R) of the thermistor and 1/T. The temperature was determined using the emf of a thermocouple.

I'm just trying to understand the equations given to us.

2. Relevant equations

R(T) = R_273(1+alpha(T - Tref)) ... coil

R(T) = a*e^(b/T) ... thermistor

3. The attempt at a solution

I've used the first equation to calculate the resistance of the coil and it all seems ok.

But I just don't get the second equation. "a" and "b" are simply stated to be constants.

From some source I found that "a" might be the intercept value on the ln(R) against 1/T graph. So I calculated it as e^(4/5) and b as 2073.68 at 218K. This seemed to match with my measured results. But I still don't know what the constants actually represent.

Is the equation a modified form of the "Steinhart Hart equation"?

Any and all help would be appreciated.

Any and all help would be appreciated

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# Homework Help: Variation of Resistance with temperature Lab experiment

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